The site had found that webpages with a “like” or “recommend” button are credited with two likes whenever the URLs are shared between Facebook users.

In other words, private Facebook messages containing shared links caused Facebook to "like" the shared webpage in the name of both the user and their friend, rather than simply increment the “like” or “recommend” count by one.

Facebook said these reports are simply not true, but acknowledged that it is fixing a glitch in its social plugin.

"Facebook is not automatically Liking any Facebook pages on a user's behalf," the Menlo Park, CA-based company said.

“We did recently find a bug with our social plugins where at times the count for the Share or Like goes up by two, and we are working on fix to solve the issue now.”

Many commercial and individual websites now use those buttons to help boost their popularity.

“To be clear, this only affects social plugins off of Facebook and is not related to Facebook Page likes. This bug does not impact the user experience with messages or what appears on their timelines.”

Facebook acknowledged that it does scan links shared between members to parse the URL to provide a preview, and to ensure the message is not spam. However, no user data is ever exposed in the process, the company said.

“Absolutely no private information has been exposed and Facebook is not automatically Liking any Facebook Pages on a user´s behalf,” Facebook told Slashgear.

“Many websites that use Facebook´s ℠Like´, ℠Recommend´, or ℠Share´ buttons also carry a counter next to them. This counter reflects the number of times people have clicked those buttons and also the number of times people have shared that page´s link on Facebook. When the count is increased via shares over private messages, no user information is exchanged, and privacy settings of content are unaffected. Links shared through messages do not affect the Like count on Facebook Pages.”